Quickie, AutoCAD program for beginners: When drawing in 2D, what axis do you NOT work with?

Z- axis in not required in2-D environment.

Z axis even if you change the axis you are working with .2d working in the X , Y and even when changing to3D working in X and Y but with changing the direction of the axis 

Z -axis do not work for2D

b. Y

z